The overall objective of the proposed research is to further our understanding of the mechanism of protein biosynthesis, and study the role of the different factors required for the translation of messenger RNA. In addition, we are interested in determining which factors are responsible for the regulation of protein synthesis during encystment and development of Artemia embryos. In the following year our research aims include: a. An examination of the conformational changes of E. coli 30S and 50S ribosomal subunits following their interaction with chain initiation factor 3 and ribosomal protein S1. b. Both dormant and developing embryos of the brine shrimp Artemia contain two factors, Co-eIF-2(A) and Co-eIF-2(B), which stimulate eIF-2 activity. Direct complex formation between eIF-2 and these factors will be determined. The factors will also be examined for stimulating the release of eIF-2-GDP from the 40S ribosomal subunit and for recycling eIF-2. The function of these factors in relation to the activity of phosphorylated eIF-2 will be assayed. c. Isolation and characterization of chain initiation factor 3 from dormant and developing embryos of Artemia.